A white bean puree -- creamy, sweet, and mellow -- is an invisible addition to vanilla cupcakes.
Preheat oven to 350 degrees, with racks in middle and lower thirds. Line 24 standard muffin cups with paper liners. In a large bowl, whisk together flour, baking powder, baking soda, and salt. In a food processor, combine beans, butter, and granulated sugar; process until smooth. With machine running, add eggs and egg whites and process until incorporated. Stir into flour mixture until well combined. Stir in buttermilk and vanilla.
Divide batter among muffin cups and bake until puffed and set, about 17 minutes, rotating pans halfway through. Transfer cupcakes to wire racks and let cool completely. (Store in an airtight container, up to 3 days.)
Whisk together confectioners' sugar and fruit puree until smooth. Dip top of each cupcake into glaze, letting excess drip off. Let glaze set, about 15 minutes, before serving.
We used pitted cherries and raspberries for the glaze, but other fruits work, too. Puree the fruit in a blender until smooth, then pass it through a fine-mesh sieve.